Acontias wakkerstroomensis, Conradie & Busschau & Edwards, 2018

Conradie, Werner, Busschau, Theo & Edwards, Shelley, 2018, Two new species of Acontias (Acontinae, Scincidae) from the Mpumalanga Highveld escarpment of South Africa, Zootaxa 4429 (1), pp. 89-106 : 99-100

Acontias wakkerstroomensis sp. nov.

Suggested common name: Wakkerstroom Legless Skink

Fig 5D , 6D , 7D

Synonym. Acontias breviceps— FitzSimons 1943 (part); Broadley & Greer 1969 (part); Branch 1988, 1994, 1998; Bates et al. 2014 (part).

Holotype. PEM R22788 , north of Wakkerstroom on Amersfoort road , Mpumalanga, South Africa (- 27.28250 S 30.11750 E, 2730 AC, 1847 m asl) collected by Werner Conradie, Christa Conradie and Melt Morrison on 23 December 2015.

Paratype. NMB R08611, north of Wakkerstroom on Amersfoort road, Mpumalanga, South Africa (-27.28250 S 30.1175 E, 2730AC, 1847 m asl) collected by Michael Cunningham on 29 September 2000.

Additional material examined (7). The following additional material was used to expand the description of variation: TM 4436-7, 11201, 11204, 11208, 11212 (Kastrol Nek); TM 61771 (Farm Paardeplaats).

Diagnosis. A medium sized legless skink assigned to the genus Acontias (part) based on body being moderately attenuate, snout not strongly acutely angled, movable eyelids present, lower eyelid immovable, and overall genetic placement ( Lamb et al. 2010). Distinguished from A. jappi , A. kgalagadi , A. lineatus (previously included in Typhlosaurus ), and A. schmitzi in possessing moveable eyelids. It can be distinguished from other congeners possessing moveable eyelids by: ventral pigmentation concentrated at the posterior margins of the scales, giving a checkered appearance (all species except A. breviceps and A. albigularis sp. nov.), compared to dorsally and ventrally uniform ( A. plumbeus , A. occidentalis (part)) or no ventral pigmentation ( A. gracilicauda , A. meleagris complex, A. lineacauda , A. occidentalis (part), A. namaquensis , and A. percivali ). It differs from A. albigularis sp. nov. by having ventral pigmentation, which is present from head to tail tip (vs unpigmented throat and cloacal region); higher number of average scales around midbody (16 scales vs 14 in A. albigularis sp. nov.). It has a near identical ventral pigmentation and the same number of average midbody scale rows (16) as A. breviceps , but differs by having a lower number of average ventral sales (151 vs 162); higher number of average subcaudal scales (37 vs 32); second upper labial touching the eye more frequently (40% vs 5%); large allopatric distribution ( A. breviceps is restricted to the Eastern Cape Province vs southern Mpumalanga); slightly lower average body vertebrae (70 vs 73); slightly higher average tail vertebrae (24 vs 22). In the phylogenetic analysis, it is sister to A. gracilicauda , from which it differs by 2.4 ± 0.6 % (16S mtDNA) and 3.3 ± 0.6 % (Cytb mtDNA) sequence divergence. It further differs 6.7 ± 1.2% (16S) and 7.3 ± 0.9 % (Cytb) from A. breviceps , and 2.1 ± 0.8 % (16S) and 3.6 ± 0.9 % (Cytb) from A. albigularis sp. nov.

Description of Holotype. A medium sized Acontias species with a total length of 209 mm (175 mm SVL; 34 mm TL). Body cylindrical, slightly flattened dorsally (probably an artefact of preservation). Head short (8.7% SVL) and narrow (HW 7.6 mm). Snout rounded and very short. Large rostral with the nostril pierced in the anterior part, connected with the border of the rostral by a straight, narrow suture. Three supraoculars present, first much larger than other. Four supracilliars, 1 st largest and 3rd smallest. Ocular exposed. Four upper labials present, the second upper labial narrowly excluded from the ocular and barely touching lip, the third and fourth well excluded from ocular by three suboculars. Three lower labials. Loreal large, in contact with the first upper labial ventrally, the rostral dorsally and preocular anteriorly. Dorsally, the rostral is followed by two enlarged head scales (prefrontal and frontal). Prefrontal large and subrectangular in shape, frontal more or less pentagonal, larger than the prefrontal and posteriorly bordered by two large parietal scales separated by an interparietal. The two parietal scales in contact anteriorly and running more or less parallel on their sides. Two narrow longitudinal scales bordering the two parietal scales. The pineal eye is pierced in the posterior part of the interparietal scale. Mental large, bordered by three chin shields, outer two scales much longer than median scale and one lower labial scale on each side of the head. Body scales homogeneous (except in size and shape- see below) and smooth in 16 rows around midbody (16 front, 16 middle, 14 anterior), 176 longitudinal scale rows (from chin shield to precloacal scale), and 35 subcaudal scales. The vertebral row of scales on the nape is equal in size, but posteriorly becoming noticeably broader. The median row of ventral subcaudal scales is strongly broadened. The first 6 subcaudal scales are split, after which the broadened scale runs all the way to the tail tip. The mid tail scale row count is seven.

Colouration in life. Dorsally olive to olive-brown in colour, with the terminal margins of the scales spotted with dark brown to black. Ventrally lighter olive-yellow, with scales spotted (similar to A. breviceps ). Cloacal shield immaculate white. The vertebral count is 70 + 24 (trunk + tail) ( Fig. 7D ).

Variation. SVL range from 83-180 mm; TL varies from 17.9-37.7 mm; HL varies from 6.9-15.7 mm; HW varies from 4.1-8.7 mm; midbody scale rows vary from 16-17 (mostly 16), ventrals vary from 149-176; subcaudals vary from 35-39; vertebrae (body) = 69-72; vertebrae (tail) = 24. Table 1 further summarises the measurements and scalation. All material examined have pigmentation concentrated on posterior margins of the ventral scales, except for the paratype in which the throat is nearly clear from any markings, similar to A. albigularis sp. nov.

Etymology. The new species is named after Wakkerstroom, which is a very small village situated in the south of Mpumalanga. The name is Afrikaans in origin and translates literally to ‘Awake-stream’. Wakkerstroom is well known by birders for its excellent birding.

Habitat. The two voucher type specimens were found under rocks in flat grasslands. Two further specimens were found on top of Ossewakop outside the town of Wakkerstroom at an altitude of 2140 m. The exact localities of the Kastrol Nek and Farm Paardeplaats records are unknown, but are believed to also be associated with grasslands.

Breeding. Two females collected from Kastrol Nek in January, each contained two well-developed embryos up to 64 mm total length ( FitzSimons 1943, Branch 1998).

Distribution and conservation. Currently only known from south-eastern Mpumalanga and adjacent KwaZulu-Natal provinces of South Africa. We assign the following historical records to A. wakkerstroomensis sp. nov.: Kastrol Nek west of Wakkerstroom (TM 4436-41, 11201, 11204, 11208, 11212); Farm Paardeplaats (TM 61771); Piet Retief (PEM 1442/35). The latter specimen is unaccounted for in the PEM and thus tentatively assigned to this species.

Figures

FIGURE 5. Four species of Acontias in life. (A) Acontias albigularis sp. nov. (PEM R20662) from Long Tom Pass, Mpumalanga Province. (B) Acontias breviceps (PEM R19010) from Hogsback, Eastern Cape Province. (C) Acontias gracilicauda (PEM R20170) from Groendal, Eastern Cape Province. (D) Acontias wakkerstroomensis sp. nov. (holotype - PEM R22788) from near Wakkerstroom, Mpumalanga Province.

FIGURE 6. Dorsal and ventral photos of the holotypes/lectotypes of the four species of Acontias discussed in this study. (A) Acontias albigularis sp. nov. PEM R20655 from Long Tom Pass, Mpumalanga Province. (B) Acontias breviceps PEM R5570 from Hogsback, Eastern Cape Province. (C) Acontias gracilicauda PEM R5131 from Grahamstown, Eastern Cape Province. (D) Acontias wakkerstroomensis sp. nov. PEM R22788 from near Wakkerstroom, Mpumalanga Province. Scale bar = one centimeter.

FIGURE 7. X-rays of the five species of Acontias discussed in this study. (A) Acontias albigularis sp. nov. PEM R20658. (B) Acontias breviceps PEM R18912. (C) Acontias gracilicauda PEM R20214. (D) Acontias wakkerstroomensis sp. nov. PEM R22788. (E) Acontias meleagris PEM R2507.